Implantable cardioverter/defibrillator programming parameters. Devices were programmed to deliver 10 ATP attempts for FVT cycle lengths (CL) of 250–300 ms. For CL <250 ms (i.e.>240 b.p.m.), high-energy shocks alone were delivered. Supra-ventricular tachycardia (SVT) discriminators, were programmed up to 240 b.p.m. ATP, antitachycardia pacing; b.p.m. beats per minute; CL, cycle length; ES, extrastimuli; FVT, fast ventricular tachycardia; SVT, supraventricular tachycardia; VF, ventricular fibrillation; VT, ventricular tachycardia.